Field aliases not available for custom popup content?

[Andy_Morgan]

JS API version 4.12

I'm generating my own custom popup content, specific to each sublayer in my map image layer. I don't want to hard code dozens of fields in 40+ layers like this:

content: "<tr><td>Utility ID: </td><td>{UtilityID}</td></tr>‍"‍‍

It's going to be more of a custom template with some functions applied to common fields throughout many layers.

When creating a function for the sublayer.popupTemplate's content, the only thing I have available in the graphic's attributes are field names. Can I not easily get the aliases for these features? I don't see a more direct way to do this aside from a traversing through the metadata of the entire map image layer using an esriRequest...get layer field name/alias pairs into an array. Can I avoid the overhead of an esriRequest?

// Create identify task for the specified map service
var identifyTask = new IdentifyTask(app.mapImgLyrUtil.url);

// Set the parameters for the Identify
var params = new IdentifyParameters();
params.tolerance = 10;
params.layerOption = "visible";
params.width = app.mapView.width;
params.height = app.mapView.height;

const arrExcludeFields = ["OBJECTID", "SHAPE", "SHAPE.STLENGTH()"];

function executeIdentifyTask(event) {
   params.geometry = event.mapPoint;
   params.mapExtent = app.mapView.extent;
   identifyTask
      .execute(params)
}

app.mapView.on("click", executeIdentifyTask);

app.mapView.popup = {
	dockEnabled: true,
	collapseEnabled: false,
	overwriteActions: true,
	defaultPopupTemplateEnabled: true,
	dockOptions: {
		position: "bottom-right"
	}
};


function createContent(content) {
	var graphic = content.graphic;  //graphic's attributes are FIELDNAME: {value}
	var displayContent = "";
	for (var key in graphic.attributes) {  //key is the field name
		if (arrExcludeFields.indexOf(key.toUpperCase()) == -1) {
			var attrVal = "";
			if (graphic.attributes[key]) {
				attrVal = graphic.attributes[key];
			}
			displayContent += key + ": " + attrVal + "<br>";
		}
	}
	return displayContent;
}


app.mapImgLyrUtil.allSublayers.map(function (sublayer) {
	sublayer.popupTemplate = new PopupTemplate({
		outFields: ["*"],
		content: createContent,
		title: sublayer.name
	});
	return sublayer;
});‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍

[BenElan]

If I am understanding you correctly, look into Arcade: Arcade | ArcGIS API for JavaScript 4.12 

Here is a sample using arcade for popups: Reference Arcade expressions in PopupTemplate | ArcGIS API for JavaScript 4.12 

[Andy_Morgan · Accepted solution]

Ben, I don't know of a way to use Arcade in a generic sense to retrieve field aliases. Can I avoid having to hard code every single field name ($feature.UtilityID, $feature.ProjectName, $feature.InstalledDate, etc...)? Hard coding expressions with specific field names for dozens of layers is out of the question. 

I was just looking for a more efficient way to translate field names to field aliases while establishing my popup templates for each of the layers.

Here's my current solution, as mentioned above, using a request against the service and building a dictionary.

var arrLayerFields = {};

esriRequest(app.mapImgLyrUtil.url + "/layers?f=json").then(function (response) {
   var layerInfos = response.data.layers;
   layerInfos.forEach(function (lyr) {
      if (lyr.type == "Feature Layer") {
         var arrFieldInfos = lyr.fields;
         arrFieldInfos.forEach(function (fieldInfo) {
            delete fieldInfo.type;    //    \
            delete fieldInfo.length;  //     } Don't need these field properties
            delete fieldInfo.domain;  //    /
         });
         arrLayerFields[lyr.name] = arrFieldInfos;
      }
    });
});‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍
//creates an object of layers with an array of fields (name and alias properties)‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍